JPH0773788B2 - Method of controlling die pressure pin of pressure casting machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pressure casting machine such as a die casting machine, and more particularly to a method for controlling a die pressure pin that re-pressurizes the molten metal filled in the die.

(Prior Art) Generally, in a pressure casting machine, volume is contracted when a molten metal is filled in a mold and solidified, and at this time, shrinkage cavities are generated inside the product, which adversely affects strength and airtightness. Especially in the die casting machine, the temperature gradient is large and shrinkage cavities are remarkable.

In order to prevent the occurrence of such shrinkage cavities, the sixth
As shown in the figure, the molten metal in the mold 101 is pressed by the pressure pin 100.
102 is repressurized to homogenize the tissue.

As a control method of the pressurizing pin 100, the injection pressure is detected by the injection pressure detecting sensor 103, and when the predetermined pressure is reached, the solenoid valve 105 for controlling the drive of the pressurizing pin 100 is excited through the control panel 104. Pressurizing pin cylinder 1
Was driving 06.

(Problems to be Solved by the Invention) In such a die casting machine, the function particularly required for the pressure pin 100 is that the re-pressurization timing by the pressure pin 100 is set because the solidification speed of the molten metal 102 is extremely high. It is to make the repressurizing effect effective by setting the optimum time.
That is, an effective re-pressurizing effect cannot be obtained if the timing of re-pressurizing is too early or too late. Further, since the coagulation time is short, the allowable range of the timing is extremely narrow.

The timing for starting the pressure pin 100 according to the conventional technique is set by the injection pressure detection sensor 103 of the die casting machine.
It is difficult to obtain an effective timing because it is performed only by the signal from, and the pushing depth of the pressure pin 100 of the repressurization part of the cast product is measured, and the measured value and the pressure pin 100 The strokes were compared, and the timing setting for starting the pressure pin 100 was changed.

However, the relationship between the stroke of the pressure pin 100 and the set value of the timing at which the pressure pin 100 is started is complicated, and the setting must be done by trial and error, which takes a very long time. In particular, it is necessary to change the timing setting for each mold and each casting condition, which requires a great deal of labor.

Further, even if the set value of the timing is determined, the solidified state of the molten metal 102 changes due to changes in the mold temperature and the like.
Furthermore, since the die casting machine is also affected by the temperature of the hydraulic oil, the relationship between the stroke of the pressure pin 100 and the set value of the start timing deviates from the initial setting, and as a result, the pressing depth of the pressure pin 100 becomes smaller. There was a problem that they were out of the allowable range, and it took a huge amount of labor to manage them.

One of the factors is that the control signal is due to the programmable controller in the control panel 104 that controls the drive of the die casting machine, so the scanning time of each relay and the like that make up the sequence is added, the response is slow, and the variation is large. There was a problem of becoming.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to quickly and easily set the start timing of the pressure pin and to stably maintain the timing. An object of the present invention is to provide a method for controlling a die pressure pin of a pressure casting machine to be obtained.

(Means for Solving the Problems) In order to achieve the above object, according to the present invention, a mold of a pressure casting machine that re-pressurizes the molten metal filled in the cavity of the mold with a pressure pin is used. In the press pin control method, a dedicated controller having a microcomputer is provided, and a predetermined injection pressure, a predetermined injection speed, a predetermined injection stroke or the like timer start reference, the optimum stroke, and the start timing time, By inputting the correction unit time of the start timing time, the number of shots for correction, the code number of the mold, etc. to start casting, and detecting the timer start reference such as the predetermined injection pressure, injection speed, injection stroke, etc. When the timer is started, the pressurizing pin is started and repressurized when the start timing time is reached, and after the repressurization is completed, the stroke detected by the stroke detecting means is detected. And the set value / optimal stroke are compared, and the start timing time is added / subtracted and corrected by the correction unit time so as to obtain the optimum stroke.

(Operation) In the method for controlling the die pressure pin of the pressure casting machine having the above-described configuration, the criterion for determining whether repressurization is effective is to detect the stroke of the pressure pin. That is, by providing a dedicated controller inside the microcomputer to set the injection pressure (Po) and the optimum stroke (So) of the pressure pin,
A comparison is made with the stroke actually detected, and feedback is applied to the start timing time at which the pressurizing pin start signal is output based on that value, and the set value of the start timing time is automatically corrected.

Here, if the stroke of the pressure pin is smaller than the stroke set value of the pressure pin, it means that the coagulation is completed before the pressure pin reaches the set stroke, so the timing of releasing the pressure pin is Revise the setting value of the start timing time of the pressure pin to make it faster.

On the contrary, if the stroke of the pressure pin is larger than the stroke setting value of the pressure pin, it means that the portion to be repressurized is being repressurized before it solidifies. Revise the set value of the start timing time so that the timing becomes late.

In addition, by directly transmitting to the drive control unit of the pressurizing pin from the dedicated controller that sets the start timing time, the delay of the response speed due to the scanning time due to the use of the programmable controller and the influence of its variation are eliminated, and more start The timing can be stabilized.

In addition, the data is stored in a storage device together with the mold code number (or lot number), and in the next lot, the optimum data can be set automatically by simply entering the mold mode number, etc. Can be converted.

(Example) Below, this invention is demonstrated based on the Example shown in figure. Second
The figure shows the main structure of a die casting machine to which the pressing pin control method of the present invention is applied. In the figure, reference numeral 1 denotes a mold, and a molten metal 4 is poured into a cavity 2 of the mold 1 from an injection sleeve 3.

The mold 1 is composed of a movable mold 5 and a fixed mold 6. The movable mold 5 is attached to a movable plate 51 of a die casting machine, while the fixed mold 6 is attached to a fixed plate 61, and the movable plate 51 is moved. It is designed to perform mold clamping and mold opening.

The injection sleeve 3 is attached to the stationary platen 61, and the opening of the tip thereof communicates with the inside of the cavity 2 of the mold 1 through the gate portion 7. The injection plunger 8 inserted into the injection sleeve 3 inserts the molten metal therein. 4 is shot. The injection plunger 8 is driven and controlled by an injection cylinder 9 arranged coaxially with the injection sleeve 3. An injection pressure detection sensor 10 is provided on the injection cylinder 9.

The mold 1 includes a pressure pin 11 and a pressure pin cylinder 12 for driving the pressure pin 11 between the movable mold 5 and the movable plate 51.

The pressure pin 11 is inserted into a pin hole 13 formed in the movable die 5, and the tip of the pressure pin 11 can project into the cavity 2. The pressure pin cylinder 12 and the pressure pin 11 are coaxial with each other. It is arranged.

A stroke detection sensor 14 for detecting the stroke of the pressure pin 11 is provided. This stroke detection sensor 14 is an absolute displacement detector,
A differential transformer is used in this embodiment. Since the absolute type stroke detection sensor 14 determines the origin position by the sensor itself, the output value at a certain stroke is always constant. In this embodiment, the stroke detection sensor 14 is housed in the pressure pin cylinder 12.

That is, as shown in FIG. 3, the coil portion 16 is fixed to the cylinder head 15 of the pressurizing pin cylinder 12, and the piston 17
A sleeve-shaped core 18 is built in so as to cover the coil portion 16. When the piston 17 moves, the built-in sleeve core 18 also moves, so that the positional relationship between the coil portion 16 and the sleeve core 18 is deviated, and a voltage corresponding to the position of the piston 17 is output. Since the piston 17 and the pressure pin 11 are integrally connected, the piston 17
The stroke of the pressure pin 11 can be detected by detecting the position of.

In this way, the absolute stroke detection sensor
By using the pressure pin cylinder 12 with 14 built-in,
The space dedicated to the stroke detection sensor 14 can be made small, and the restriction due to the pressure pin unit of the mold 1 can be minimized in terms of space. That is, generally, the gap between the movable die 5 of the die 1 in which the pressurizing pin cylinder 12 is arranged and the movable plate 51 is small, and the space limitation is large. By incorporating the pressure pin cylinder 12 in the space, it is possible to save space.

The stroke detection sensor 14 is not limited to the absolute type, but an incremental type may be used, but the incremental type requires a signal of the origin position, and there is a space and environmental problem. Is preferred.

Then, the stroke detection sensor 14 and the injection pressure detection sensor 10 are connected to the input device 21 of the controller 20, which is a control means, and each output signal is input. The controller 20 includes a central processing unit (CPU) 2 in addition to the input device 21.
2. A storage device (memory) 23 and an output device 24 are provided.

The output device 24 is directly connected to a solenoid valve 26 that drives and controls the pressurizing pin cylinder 12 through an amplifier 25.

Further, 27 is an input device such as a keyboard, and the pressure pin 11
Is connected to the controller 20 in order to input various information such as the setting of the optimum stroke So.

As shown in FIG. 5, the control of the pressurizing pin 11 is performed by the injection pressure P.
Has reached a predetermined set pressure Po, that is, at the time of pressure increase switching in this diagram, a start timer 201 described later is activated. Then, when the predetermined start timing time To has elapsed and the time is up, a start signal is output to switch the solenoid valve 26, and the pressurizing pin cylinder 12 is operated to start the pressurizing pin 11 to repressurize. It is something to do.

FIG. 4 shows a control block diagram of the controller 20.

That is, the stroke detection sensor 14 causes the pressure pin 11 to
Detects the actual stroke Sa of this
Is fed back to compare whether or not it is within the allowable range So ± α of the optimum stroke So stored in the storage device 23, and based on the comparison result, the start timing time correction means 200 determines the start timing time. Set value T
The minute time unit ΔT stored in the storage device 23 is added to or subtracted from o to correct it, and the process proceeds to the next step.

Then, the corrected start timing time is set as the time-up time of the start timer 201, and when the injection pressure P reaches the predetermined injection pressure Po stored in the storage device 23, the start timer 20
1 is set and a start signal is transmitted to the solenoid valve 26 after the corrected start timing time To has elapsed. Further, the pressurizing pin cylinder 12 is driven to detect the stroke of the pressurizing pin 11 and the detected value is fed back, and the injection process is sequentially repeated to make the injection stroke Sa of the pressing pin 11 the optimum injection stroke So allowable range So. It is automatically controlled to be within ± α.

The control of the pressure pin will be described in detail below with reference to the flowchart of FIG.

First, given injection pressure Po, optimum stroke So, allowable range of optimum stroke So ± α, code No. of mold 1, start timer 2
Start timing time T ₀ , which is the time-up time of 01, and minute time unit ΔT, which is the correction unit of start timing time T ₀ ,
The number of shots n, which is the data to be corrected, is preset (step 1), and the injection operation is started (step 2).

Then, the injection pressure P detected by the injection pressure sensor 10 is input from the input device 21 of the controller 20, and the injection pressure P is preset in the storage device 23 as a predetermined injection pressure Po.
When the start timer 201 is reached, the start timer 201 is set (step 3,
Four).

Next, it is judged whether or not the start timer 201 has timed out (step 4), and when the time is up, a start signal for starting the pressurizing pin 11 is sent to the solenoid valve 26 through the output device 24. As a result, the solenoid valve 26 is switched to drive the pressurizing pin cylinder 12, the pressurizing pin 11 is started, and re-pressurization of the molten metal 4 in the die 1 is started (step 5).

The molten metal 4 to be repressurized is in the stage of solidification, and when the solidification progresses, the pressurizing pin 11 does not further advance and stops. The pressure pin stroke Sa at the time of this stop is detected by the stroke detection sensor 14 and compared with the optimum stroke So stored in the storage device 23 in the central processing unit 22, and the detected stroke Sa is the allowable stroke So. Range So
It is determined whether it is within ± α (step 7).

Then, if the detected stroke Sa is within the allowable range, the start timing time To set initially is stored in the storage device 23,
(Step 10), the next injection process is started.

If the detected stroke Sa is not within the allowable range, the start timing time To is corrected and the next injection process is started. The start timing time is corrected by adding or subtracting a preset minute time unit ΔT to To (step 9).

That is, when the stroke Sa of the pressurizing pin 11 is smaller than the allowable range So-α of the set value So, it means that the coagulation is completed before the pressurizing pin 11 reaches the set stroke So. ΔT is subtracted from the start timing time To so that the timing at which the pin 11 is output becomes early.

On the other hand, the stroke Sa of the pressure pin 11 is within the allowable range So of the set value.
If it is larger than + α, the start timing of re-pressurization is early, so ΔT is added to To so that the start timing time is delayed.

In this way, the set stroke gives a certain allowable range ± α to the preset value So, and the controller 20 constantly feeds back so that the detected actual stroke Sa of the pressurizing pin 11 falls within that range. By providing the display means 202, it is possible to display the detected stroke Sa by digital display or the like. By displaying the detected strokes in this manner, comparison and evaluation with an actual product can be easily performed.

Here, the correction process is not limited to one shot, but may be performed every several shots. In this embodiment, the number of shots n that is data is input, and the stroke determination process of step 7 and the stroke determination process of step 9 are performed. A discrimination step of discriminating the number of shots is provided between the start timing time correction step (step 8). For example, if n is set to 1, the start timing time T of the start timer 201 is set for each shot.
If o is modified and n is set to multiple, say 3,
The start timing time To is corrected based on the data of the previous two shots every three shots.

Furthermore, the data when a good product is obtained stably is stored in a storage device together with the mold code number (or lot number).
It can be set in an extremely short time because it is stored in 23 and can be automatically set as the initial value for the next casting.

Further, in the above embodiment, the start timing time of the pressurizing pin 11 is determined with reference to the predetermined injection pressure of the injection cylinder 9, but the injection speed (not shown), the predetermined injection speed by the injection stroke sensor, the predetermined injection stroke, etc. It may be used as a timer start reference for determining the start timing. The present invention is premised on that the amount of hot water supplied to the injection sleeve is stable.

(Effects of the Invention) The present invention has the above-described configuration and operation, and detects the stroke of the pressure pin and controls the start timing of the pressure pin so that the detected value becomes a predetermined stroke amount. Therefore, the start timing time of the pressurizing pin can be set in a short time, and the optimum timing can always be realized, so that the optimum repressurizing effect can be stably maintained.

In addition, it is possible to quickly reproduce the above repressurizing effect under any control such as each mold and each casting condition.

Furthermore, by directly driving and controlling the pressurizing pin from a dedicated controller incorporated in the microcomputer, the response speed is fast, and the influence of the conventional scanning time variation due to the programmable controller can be eliminated.

[Brief description of drawings]

FIG. 1 is a flow chart showing a control flow of a pressure pin control method for a pressure casting machine according to an embodiment of the present invention, and FIG. 2 is a control block diagram showing an apparatus configuration for performing the control shown in FIG. 3 is a longitudinal sectional view showing the structure of the stroke detection sensor of FIG. 2, FIG. 4 is a control block diagram by the controller of FIG. 2, and FIG. 5 is an injection pressure and a pressing force of the pressure casting machine of FIG. Diagram showing change over time of compression pin stroke, 6th
The figure is a control block diagram of a conventional pressure casting machine. Explanation of symbols 1 ... Mold, 2 ... Cavity 3 ... Injection sleeve, 4 ... Molten metal, 5 ... Movable type, 6 ... Fixed type, 8 ... Injection plunger, 9 ... Injection cylinder, 10 ... Injection pressure Detection sensor 11 …… Pressure pin 12 …… Pressure pin Cylinder, 13 …… Pin hole 14 …… Stroke detection sensor 15 …… Cylinder head, 16 …… Coil part 17 …… Piston, 18 …… Sleeve core 20… ... controller, 21 ... input device 22 ... central processing unit, 23 ... storage device 24 ... output device 200 ... start timing time correction means 201 ... start timer 202 ... display means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsu Kobayashi 2480 Kuno, Odawara-shi, Kanagawa Mikuni Industrial Co., Ltd. Odawara Plant (56) References JP-A-2-75460 (JP, A) JP-A-3-275263 ( JP, A) JP-A-3-275264 (JP, A) JP-A-2-220755 (JP, A) Actual development Sho 62-159958 (JP, U)

Claims (1)

[Claims] 1. A die pressure pin control method for a pressure casting machine for re-pressurizing the molten metal filled in a cavity of a die with a pressure pin, comprising stroke detection for detecting a stroke of the pressure pin. Means, and a dedicated controller having a microcomputer installed therein, and a timer start reference such as a predetermined injection pressure, a predetermined injection speed or a predetermined injection stroke, an optimum stroke, the start timing time, and the start timing. The unit of time correction, the number of shots for correction, the code number of the mold, etc. are input to start casting, and the timer start criterion such as the predetermined injection pressure, the predetermined injection speed, or the predetermined injection stroke is reached. The timer is started by detecting the time point, and when the start timing time is reached, the pressurizing pin is started and repressurized. A die pressing pin for a pressure casting machine, characterized in that the start timing time is added / subtracted by the correction unit time so that the stroke detected by the output means is compared with the optimum stroke to become the optimum stroke. Control method.